Etching process apparatus and member for etching process chamber

ABSTRACT

It is an object of the present invention to provide an etching process apparatus which can suppress evolution of foreign matter to improve production yield. 
     An etching process apparatus comprising:
         a vacuum container and a process chamber inside of the vacuum container, in which a sample set in the process chamber held in the vacuum container is etched by the use of plasma;   a member held inside of the process chamber; and   a coating film which is formed by spray-coating a given material and covers a surface of the member and is exposed to the plasma, wherein, in a surface thereof, pores therein are sealed by the use of a material same as the given material.

FIELD OF THE INVENTION

The present invention relates to an etching process apparatus for processing a substrate-shape sample, e.g., semiconductor wafer, in a vacuum chamber, and a member which constitutes an etching process chamber, more specifically an etching process apparatus whose member, e.g., inner wall, has a surface exposed to a plasma is coated with a film more resistant to plasma than the member, and member which constitutes the etching process chamber.

BACKGROUND OF THE INVENTION

It is known that an etching process apparatus has improved resistance to plasma by coating the etching process chamber container with a sprayed coating film of Y₂O₃ or the like having a porosity of 5 to 10%, as disclosed by JP-A-2001-164354 (Patent Document 1).

BRIEF SUMMARY OF THE INVENTION

Processes for producing semiconductor devices, liquid-crystal displays and so forth have generally problems of notable corrosion-caused depletion of inner wall materials for etching process containers, because they use treat gases, beginning with fluorides, e.g., SF₆ and CF₄, chlorides, e.g., BCl₃ and SiCl₄, and bromides, e.g., HBr. Surfaces of members in etching process chamber insides have been coated with a film to be protected from interactions with a plasma, the films being formed by spraying a ceramic material, e.g., quartz or alumina, and by anodic oxidation of aluminum alloys. For example, materials for inner walls of plasma process containers for semiconductor production facilities include metallic materials, e.g., Al, Al alloys and stainless alloys, as bases which are coated with Al by anodic oxidation; borocarbide or alumina by spraying; material such as SiO₂ and SiC; or high-molecular-weight compounds, e.g., fluororesin or epoxy resin.

These materials, when exposed to highly corrosive halogen ions, are chemically damaged to produce fine SiO₂, Al₂O₃ particles or the like. It is also known that they are eroded by the plasma-excited ions. An etching process which uses a halogen compound gas, in particular, is frequently aided by a plasma to further activate the process by the reactions. In a plasma atmosphere, a halogen compound is dissociated into atomic F, Cl, Br or the like, which is highly corrosive. At the same time, members in a plasma process container are chemically damaged and eroded by fine particles simultaneously in the presence of fine solid particles of SiO₂, Al₂O₃ or the like, i.e., strongly affected by the so-called erosion/corrosion effects. Moreover, in an etching process chamber in which a plasma is excited, even a non-corrosive gas, e.g., Ar, may be ionized to cause ion bombardment, a phenomenon in which a solid surface is strongly bombarded with the ionized gas. It is therefore known that each member in the container is damaged more strongly.

The technique disclosed by JP-A-2001-164354 is expected to alleviate plasma-caused damages of etching process chamber surfaces exposed to a plasma, because they are coated with a sprayed coating film of Y₂O₃ or the like. Moreover, it includes a 50 to 500 μm thick metallic film as an undercoat which covers a base material. However, it makes no mention of surface roughness of a base material coated with a sprayed coating film, except giving some mentions of adhesion of the sprayed coating film.

JP-A-2001-164354 fails to fully take into consideration, for an etching process chamber whose internal members are coated with a ceramic material, e.g., Al₂O₃ or Y₂O₃, an increased foreign matter coming from the sprayed coating film material itself and contamination therewith.

More specifically, when a plasma is actually generated in an etching process chamber whose internal members are coated by the above-described surface treatment, the plasma will have an increased ground potential. In other words, etching process chamber surfaces exposed to a plasma are coated with an insulating material, with the result that the plasma cannot be grounded. Moreover, the fine particles of the sprayed coating film material present on the sprayed coating film surfaces or in the pores of the film may be charged to scatter into the chamber. Still more, the sprayed coating film, which has surface irregularities, may partly separate at projected portions or weakly bonded portions to scatter into the chamber. The sprayed coating film may be treated to seal the pores to contain the fine particles in the sprayed coating film therein. However, the sealing material is not the same as that for the sprayed coating film, and may be depleted faster than the film, with the result that the film goes back to the state before the treatment, to increase contaminants mainly of fine particles of a chemical component of the sprayed coating film.

An internal member coated with a sprayed coating film for an etching process chamber is set in an etching process apparatus after being cleaned, normally by a combination of supersonic waves, blasting, spraying of compressed water, immersion in a solvent or pure water, and so forth. However, it is difficult to completely wash out fine foreign particles of the sprayed coating film material out of the film.

The inventors of the present invention have studied to solve the above problems to find that foreign matter coming from a sprayed coating film material is frequently caused by a process for forming the sprayed coating film. For example, a material to be sprayed may be completely molten while traveling from a sprayer to a surface to be coated, or reaches the surface without being completely molten, depending on particle size of a base material for the sprayed coating film. When a spraying process is designed, the spraying conditions are set such that sprayed particles having a specific size reach the surface after being molten, and particles having an actual size distribution will be partly in a molten state and partly in a semi-molten state. In other words, particles having a size larger than an optimum size will reach the surface without being completely molten. On the other hand, those having a size smaller than an optimum size will be carried by a plasma jet onto the surface before it enters a high temperature zone in the spray flame center, to form a sprayed coating film in a semi-molten state, also in this case. As a result, the sprayed coating film formed on an etching device internal member has a structure with flat particles of the sprayed material deposited in layers. Such a sprayed coating film will have a number of microcracks and pores with the semi-molten particles not fast attaching to each other microscopically.

In an etching process chamber where an internal member coated with the above sprayed material is exposed to a plasma, the particles reaching the surface in a semi-molten state may be charged to scatter from a portion which constitutes a microcrack in the coating film into the etching process chamber, and so may be the particles of the sprayed coating film material present in the pores. Moreover, the particles of the sprayed material, when exposed to an inert gas, e.g., Ar, may be scattered into the chamber by the bombardment of the surface with the ions in the plasma. These phenomena increase quantity of foreign matter, which comes from the sprayed material, floating in the chamber and, hence, contamination with a chemical component of the sprayed material. Moreover, the particles scattering into the plasma may be deposited during the etching process on wafers for semiconductor devices or the like to cause failure of the devices resulting from deteriorated wiring and electric characteristics, and also cause deteriorated etching yield for production of semiconductor devices.

Spraying conditions have been varied to find new techniques for diminishing pores and microcracks on the sprayed coating film surfaces. For example, vacuum spraying is one method for reducing sprayed coating film porosity. This method, although possibly giving a film of lower porosity than the common atmospheric spraying, involves problems resulting from cooling of the internal member coated with a sprayed coating film, and needs a film-making process including a cooling mechanism. Moreover, it invariably needs a vacuum container for holding a spraying device and spray-coated internal members, and hence is difficult to improving internal member productivity.

It is an object of the present invention to provide an etching device and internal member for etching process chamber which can suppress evolution of foreign matter to improve production yield.

The above object is achieved by diminishing pores and microcracks from surfaces of a sprayed coating film which coats a chamber internal member in an etching process apparatus.

More specifically, the above object is achieved by providing: an etching process apparatus comprising:

a vacuum container and a process chamber inside of the vacuum container, in which a sample set in the process chamber held in the vacuum container is etched by the use of plasma;

a member held inside of the process chamber; and

a coating film which is formed by spray-coating a given material and covers a surface of the member and is exposed to the plasma, wherein, in a surface thereof, pores therein are sealed by the use of a material same as the given material, and

is achieved by providing: an internal member for an etching process chamber in which a sample set in a process chamber held in a vacuum container is etched by the use of plasma, wherein the internal member comprises a coating film which is formed by spray-coating a given material and covers a surface of the member and is exposed to the plasma, wherein, in a surface thereof, pores therein are sealed by the use of a material same as the given material.

Moreover, the above object is achieved by melting the surface of the sprayed coating film on the internal member to seal the pores. It is also achieved by further coating the coating film with the same material as that for the sprayed coating film by the sol-gel process to seal the pores.

Still more, the above object is achieved by heating the coating film, which has been coated with the same material as that for the coating film, at 400 to 500° C. to seal the pores.

Still more, the material for the coating film is composed of at least one species selected from the group consisting of Al₂O₃, YAG, Y₂O₃, Gd₂O₃, Yb₂O₃ and YF₃.

Other objects, features and advantages of the invention will become apparent from the following description of the embodiments of the invention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view, cut in the longitudinal direction, illustrating an etching process apparatus structure of one embodiment of the present invention.

FIG. 2 is a cross-sectional view, cut in the longitudinal direction, illustrating the device structure shown in FIG. 1 around its etching process chamber.

FIG. 3 is a cross-sectional view, cut in the longitudinal direction, schematically illustrating the chamber shown in FIG. 2 for its inner wall structure.

FIG. 4 shows a magnified view of the section A of the inner wall shown in FIG. 3

DESCRIPTION OF REFERENCE NUMERALS

100: Process chamber, 101: Lid member, 102: Antenna, 103: Magnetic field generating section, 105: Radio wave generating source, 106: Dielectric member, 107: Quartz plate, 108: shower plate, 109: Sample table, 110: Etching process chamber, 116: Inner wall of etching process chamber, 117: Sprayed coating film, 118: Surface film, 131: Exhaust valve, 132: Exhaust pump, 150: Wafer, 200: Plasma

DETAILED DESCRIPTION OF THE INVENTION

The embodiment of the present invention relates to a sprayed surface of etching process chamber internal member for an etching process apparatus. When used for inner walls defining an etching process chamber and exposed to a plasma with which a sample, e.g., Si wafer for semiconductor devices, is etched, it suppresses evolution of foreign matter of the film material from the film surface exposed to a plasma. This can diminishes fine foreign particles scattering onto the wafer or the like, and thereby improving semiconductor device yield and productivity. Moreover, it reduces contamination of the internal member surface with foreign matter coming from the film material exposed to the plasma in the process chamber, thereby improving productivity of the etching process apparatus.

The plasma-exposed member in the process chamber for the etching process apparatus of the embodiment is coated with a film produced by spraying in air, whose surface is locally, in particular selectively, heated. This melts fine particles of the sprayed material attaching to the film surface and microcracks, and then deposits them on the film-constituting internal member and particles around them. For pores present in the coating film surface area, it locally heats the sprayed coating film surface selectively to melt surfaces of the particles of the sprayed coating film material, present in the pores to constitute them. Therefore, it can also deposit them on the near-by particles. Moreover, it heats the sprayed coating film material to a molten or semi-molten state to melt the pores and microcracks to diminish them.

For heat treatment of the sprayed coating film surface, it may be heated by a flame, or irradiated with arc, laser beams or electron beams. A combination of two or more of them may be also used. Moreover, the microcracks and pores present in the sprayed coating film on an etching process chamber internal member may be further diminished by increasing flame temperature, increasing sprayed particle speed, decreasing sprayed particle travel distance or decreasing pressure of the spraying atmosphere, while the sprayed surface vicinity is spraying-treated. This embodiment decreases porosity of the etching process chamber internal member surface to 5% or less.

The etching process chamber internal member for the etching process apparatus of the embodiment has the sprayed coating film which is further surface-treated with a material containing the same film material as a major ingredient by the sol-gel process. This treatment fills the microcracks and pores in the film surface area with the material to seal them. This treatment may be followed by local, in particular selective, heating of the film surface. This solidifies the gel-like material flowing into the microcracks and pores, and contains the particles and fine pieces in the microcracks and pores in the film surface area, together with fine particles attaching to particles spray-bonded to the above particles and fine pieces to constitute them.

In particular, the process chamber internal member of this embodiment is coated with a sprayed coating film which is further coated by the sol gel process, in which a sol containing an alkoxide of the same ceramic material as that for the coating film is hydrolyzed and polycondensed to seal the pores. This treatment diminishes surface irregularities to smoothen the surface.

Spraying the coating film with the same film material as that for the coating film reduces a difference between bulk of the sprayed coating film and the portions with the sealed pores in interactions with the plasma, thereby controlling the localized interactions. The as-smoothened film surface treated to seal the pores is more uniformly bombarded with the plasma ions or the like and ground down while keeping its surface smoothness.

The surface treatment of the sprayed coating film for the process chamber internal member can diminish foreign matter scattering out of the film while the process is proceeding, and hence can provide a plasma etching process apparatus of diminished fine particles coming from the sprayed material and reduced contamination therewith.

This embodiment for producing the etching process apparatus locally heats the plasma-exposed coating film surfaces on the etching process chamber internal member to diminish the fine particles coming from the sprayed material, present in the microcracks and pores. The spraying process may be changed for the portions near the surface of the internal member to be sprayed such that evolution of the microcracks and pores is suppressed, or treats the coating film by the sol-gel process with a material containing the sprayed material as a major ingredient to diminish the microcracks and pores present in the surface area and thereby to suppress foreign matter coming from the sprayed material scattering from the coating film while the film interacts with the plasma.

Thus, the embodiment can suppress evolution of foreign matter in the etching process chamber and hence contamination with the coating film material. As a result, it can give the device of reduced defects resulting from contamination with the film material, and also improves production efficiency. When used for an etching process chamber internal member, in particular, the sprayed coating film of the embodiment improves etching process efficiency and production yield.

EXAMPLES

One example of the present invention is described by referring to FIGS. 1, 2, 3 and 4.

FIG. 1 shows a cross-sectional view, cut in the longitudinal direction, outlining an etching process apparatus structure of this example of the present invention. As illustrated, the etching process apparatus of this example comprises a process chamber 100 which is a vacuum container containing an etching process chamber 110, and means for supplying an electrical and magnetic fields into the etching process chamber 110 to produce a plasma therein and means for supplying a treat gas into the etching process chamber 110, both means disposed above the chamber 110. It also equipped with an exhaust valve 131 and exhaust pump 132 disposed below, and in communication with, the etching process chamber 110, to exhaust the chamber.

The etching process chamber, capped by a lid member 101, comprises an antenna 102 disposed below the lid 101, and magnetic field generating section 103 disposed above and side of the antenna 102 such that it surround the etching process chamber 110, and ceiling member disposed below the antenna 102. A radio wave generating source 105 is disposed above the magnetic field generating section 103 for supplying power to the antenna 102 to emit VHF and UHF waves of 200 MHz to 1 GHz. The antenna 102 is disposed below the lid member 102 of electroconductive material, e.g., stainless steel, and a dielectric member 106 is disposed between the antenna 102 and lid member 101 to insulating them from each other and conducts the electromagnetic waves emitted from the antenna 102 towards the ceiling member below the antenna 102.

Moreover, the ceiling member has a quartz plate 107 of dielectric material, e.g., quartz and shower plate 108 disposed below the quartz plate 107, the former conducting the electromagnetic waves transmitted thereto towards the process chamber inside and the latter being provided with a plurality of holes for distributing the treat gas which it receives into the process chamber. A sample table 109 is disposed in the lower portion of the cylindrical etching process chamber 110, which is disposed below the shower plate 108. The etching process chamber 110 produces a plasma in the treat gas containing a plurality species of gases including, e.g., a halogen-base gas, in the space above the sample table 109 by the interactions between the electromagnetic waves and magnetic field, the former being supplied from the antenna 102 through the shower plate 108 and the latter being supplied from the magnetic field generating section 103. The shower plate 108 passes the treat gas into the etching process chamber 110 through its holes which are mainly disposed to face a substrate-shape sample 150, e.g., semiconductor wafer, supported by the sample table 109. This arrangement can distribute the treat gas onto the sample 150 more evenly and secure a uniform plasma density.

The cylindrical etching process chamber 110, in which the plasma is produced, is defined by a cylindrical inner wall 116 which is disposed below the shower plate 108, the inner wall 116 being exposed to the plasma and controlled at an adequate temperature on the surface during the etching process by a heater wound around the wall 116 exterior. The wafer 150 is transferred and set on a dielectric film by a robot (not shown), the dielectric film constituting the upper side of the sample table 109 in the etching process chamber 110. A DC current is applied between film-shape electrodes disposed within the dielectric film to attract and hold the wafer 150 on the sample table 109 by electrostatic force.

The lower portion of the process chamber 100 is a vacuum container defining the space below the sample table 109 whose basal plane is provided with an opening which communicates the chamber 100 with the exhaust means provided with the exhaust valve 131 and exhaust pump 132. The etching process chamber 110 inside is controlled at a given level by a balance produced between exhaust by the exhaust means and gas supply from the shower plate 108 into the etching process chamber 110.

In the etching process apparatus of the above structure, the etching process chamber wall 116 is coated with a sprayed coating film 117, capable of suppressing the interactions with the plasma, on the wall 116 portion exposed to the plasma 200 generated in the etching process chamber 110. The sprayed coating film 117, having a diminished number of the microcracks and pores in the vicinity of the surface exposed to the plasma 200 generated during the etching process, cleaning process or the like, can diminish foreign matter containing the film material as a major ingredient and remaining on the wafer 150 to be treated, e.g., by etching, and also diminish contamination with a chemical component of the film, even when the etching process chamber's inner wall 116 surface is exposed to the plasma. Hence, the etching device of the present invention can produce a semiconductor device having diminished foreign matter coming from the film material and contamination therewith on account of the sprayed coating film, and hence can have improved productivity.

FIG. 2 shows a cross-sectional view, cut in the longitudinal direction, outlining the device structure shown in FIG. 1 around its etching process chamber 110, in particular shows a magnified view of the inner wall 116 of the etching process chamber 110 illustrated in FIG. 1. It shows an example of the inner wall 116 coated with the sprayed coating film 117. The sprayed coating film 117 itself is made of a ceramic material which has very low reactivity with a process plasma and high plasma resistance. Coating the inner wall 116 in the etching process chamber 110 with a highly plasma-resistant ceramic material suppresses increase of a large quantity of foreign matter coming from the film material and remaining on the wafer 150 for semiconductor devices and of its contamination with a chemical component of the film, even when the inner wall 116 surface is exposed to the plasma 200 generated in the etching process chamber 110. In other words, it can diminish foreign matter scattering onto the wafer 150 and its contamination therewith, and hence allows the etching process apparatus to efficiently produce semiconductor devices of limited defects.

FIG. 3 shows a cross-sectional view, cut in the longitudinal direction, schematically illustrating the etching process chamber 110 shown in FIG. 2 for its inner wall structure defining the chamber 110. In particular, the sprayed coating film 117 for the present invention is disposed upstream of the wafer 150 for semiconductor devices, wherein a treat gas for the etching process, e.g., halogen-containing gas, is supplied through the shower plate. Use of the etching process chamber internal member coated with the sprayed coating film 117 can diminish foreign matter coming from the wall and contamination therewith.

In the embodiment, the sprayed coating film 117 treated to seal the pores is positioned upstream (upper side in the figure) of the wafer for semiconductor devices, set on the sample table 109. This can efficiently diminish contamination with foreign matter of a material containing the film material as a major ingredient and that coming from a component scattered from the film. In other words, foreign matter coming from the sprayed coating film which coats the etching process apparatus internal member downstream of the sample table on which the wafer for semiconductor devices is set is prevented from scattering onto the wafer 150, because it is carried by a process gas discharged under a vacuum even when it scatters from the sprayed coating film damaged by the plasma 200 generated in the etching process chamber 110. Hence, the device of the above structure can prevent foreign matter coming from the sprayed film from scattering onto the wafer 150 being treated by etching or the like, and contamination with a chemical component of the sprayed coating film, and can efficiently produce the semiconductor devices of limited defects.

FIG. 4 schematically illustrates the sprayed coating film which coats the etching process chamber 110 internal member, showing a magnified view of the section A in the etching process chamber's inner wall 116, shown in FIG. 3. The film 117 coating the inner wall 116 is totally formed by a ceramic material powder containing at least one species selected from the group consisting of Al₂O₃, YAG, Y₂O₃, Gd₂O₃, Yb₂O₃, and YF₃, sprayed onto the inner wall 116 in air using a plasma. The sprayed coating film 117 is bonded to the inner wall 116 by the anchor effect produced by a number of the ceramic particles fused to a base material 116′ of aluminum or aluminum alloy.

Moreover, the sprayed coating film 117 is coated with a surface film 118, treated to diminish the pores and microcracks, to suppress scattering of the particles of the sprayed coating film material. The surface film 118 is formed by locally, in particular selectively, heating the sprayed coating film 117 formed, or by treating the sprayed coating film 117 surface by the sol gel process, in which a sol containing an alkoxide of the same ceramic material as that for the coating film is hydrolyzed and polycondensed to seal the pores.

In particular, the sol-gel process for the embodiment sprays a gel of an alkoxide of the same ceramic material as that for the sprayed coating film 117 onto the sprayed coating film 117, or immerses the inner wall 116 masked on the portion which is not exposed to a plasma in the above gel held in a given container to form the gel film on the portion which is exposed to a plasma. Then, the sprayed coating film 117 coated with the alkoxide film is heated at 400 to 500° C. for a given time selectively for the surface to form the surface film 118 by evaporating the volatile materials by thermal decomposition and polycondensation.

In the embodiment, the sprayed coating film 117 is produced under the spraying conditions which can increase porosity to a level to suppress evolution of cracks by thermal shock and secure adhesion at an adequate strength to the base material 116′. The surface has a structure of improved resistance to plasma and corrosion by the surface film 118, to diminish defects and damages of the sprayed coating film 117 and evolution of foreign matter. In particular, the embodiment fuses fine particles of the sprayed material deposited on the film and microcracks to deposit them on the ambient members which constitute the coating film and on the particles.

It also can diminish the pores in the coating film surface area by locally heating the sprayed coating film surface selectively to fuse the particles of the sprayed material attaching to the sprayed particles which constitute the pores in the surface area, to deposit them on the ambient particles. Moreover, it heats the particles of the sprayed material to a molten or semi-molten state to melt the pores and microcracks to diminish them.

Moreover, the microcaracks and pores in the sprayed coating film 117 surface area are filled and sealed with the same material as that for the sprayed coating film 117. Then, the film 117 is locally heated, in particular selectively in the surface area, to solidify the gel-like material flowing into and sealing the microcaracks and pores to contain the particles and fine pieces in the microcracks and pores in the film surface area, together with fine particles attaching to particles spray-bonded to the above particles and fine pieces to constitute them.

The microcaracks and pores in the sprayed coating film 117 may be diminished by adopting at least one measure of increasing spraying flame temperature, increasing sprayed material particle speed, decreasing the travel distance of the particles, decreasing pressure of the spraying atmosphere or the like for forming the surface film 118, to transform the sprayed material into a molten state. In the embodiment, porosity of the surface film 118 is set at 5% or less, and that of the sprayed coating film 117 below the film 118 is at 7% or more, preferably 10% or more.

The etching process apparatus of the above structure can suppress evolution of foreign matter from the etching process chamber's inner wall 116, diminish foreign matter scattering onto the wafer 150 treated in the etching process chamber 110, and diminish contamination with a chemical component coming from the foreign matter, to efficiently produce semiconductor devices of limited defects.

As discussed above, the embodiment diminishes the pores and microcracks in the sprayed coating film which coats the etching process chamber 110 internal member to suppress scattering of foreign matter from the sprayed coating film on which it is deposited and from the sprayed coating film damaged when exposed to a plasma. Hence, it diminishes foreign matter coming from the sprayed coating film material and contamination with a chemical component of the sprayed coating film material. As a result, it can achieve the object of producing the devices of limited defects resulting from foreign matter and contamination therewith.

It should be further understood by those skilled in the art that although the foregoing description has been made on embodiments of the invention, the invention is not limited thereto and various changes and modifications may be made without departing from the spirit of the invention and the scope of the appended claims. 

1. An etching process apparatus comprising: a vacuum container and a process chamber inside of the vacuum container, in which a sample set in the process chamber held in the vacuum container is etched by the use of plasma; a member held inside of the process chamber; and a coating film which is formed by spray-coating a given material and covers a surface of the member and is exposed to the plasma, wherein, in a surface thereof, pores therein are sealed by the use of a material same as the given material.
 2. The etching process apparatus according to claim 1, wherein the coating film is formed by spraying the given material and then treated to melt the surface to seal the pores.
 3. The etching process apparatus according to claim 1, wherein the coating film is formed by spraying the given material and then coated with the same material as that for the coating film by the sol-gel process to seal the pores.
 4. The etching process apparatus according to claim 3, wherein the coating film coated with the same material as that for the coating film is heated at 400 to 500° C. to seal the pores.
 5. The etching process apparatus according to one of claims 1 to 4, wherein the material for the coating film is composed of at least one species selected from the group consisting of Al₂O₃, YAG, Y₂O₃, Gd₂O₃, Yb₂O₃ and YF₃.
 6. The etching process apparatus according to claim 2, wherein the coating film formed by spraying the given material is heated by a flame, or irradiated with arc, laser beams or electron beams, or a combination thereof, to melt the surface and seal the pores.
 7. An internal member for an etching process chamber in which a sample set in a process chamber held in a vacuum container is etched by the use of plasma, wherein the internal member comprises a coating film which is formed by spray-coating a given material and covers a surface of the member and is exposed to the plasma, wherein, in a surface thereof, pores therein are sealed by the use of a material same as the given material.
 8. The internal member for an etching process chamber according to claim 7, wherein the coating film is formed by spraying and then treated to melt the surface to seal the pores.
 9. The internal member for an etching process chamber according to claim 7, wherein the coating film is formed by spraying and then coated with the same material as that for the coating film by the sol-gel process to seal the pores.
 10. The internal member for an etching process chamber according to claim 9, wherein the coating film coated with the same material as that for the coating film is heated at 400 to 500° C. to seal the pores. 